Anchoring systems are generally known in which a stranded flexible cable having a tensile strength exceeding 800 lbs. is used to mechanically connect the handset to the housing. The stranded cable together with the telephone signal wires are sheathed in a flexible telephone cord armor between the handset and the housing. The stranded cable extends through the yoke of the handset past the junction of the yoke and handset receiver portion. The end of the stranded cable is provided with an end plug or stop. The known prior retainer members have been either wedge-shaped to engage the yoke receiver junction or of a curved compound surface which matches the shape of the yoke-receiver junction. In each of these retainers, there is provided a pocket in which the end plug seats when the stranded cable is stressed.
The prior art retainer members suffer from numerous disadvantages. The wedge-shaped retainer member exerts forces against the interior of the handset which are greater than the force in the stranded cable in accordance with the principle of the inclined plane. The forces are applied where the handset is weak and are not aligned with the applied force. Therefore, while a wedge-shaped surface is simple and relatively inexpensive to produce, it allows the handset to rupture and perhaps injure the user. Alternatively, the compound curved surface retainer members are formed so as to closely match the interior surface of the yoke-receiver portion of the handset so as to distribute the forces over a large surface area when the handset is pulled away from the housing. These devices thus require the machining of a compound convex/concave tool surface which is expensive.
Still further, a problem with the known prior art retainer members is that the end plug, which under stress rests within the pocket provided in the retainer member, can be displaced from the pocket when the handset is not under stress or alternately is compressed toward the housing. In this case, the end plug interferes with the handset receiver and can cause damage to the receiver and telephone wires. This is especially true when a displaced end plug is subsequently placed under stress and entangles the telephone wires or the receiver terminals. In this case, the wires can be crimped, shorted or otherwise damaged.
There is therefore needed a retainer member which provides sufficient tensile strength for anchoring the handset to the housing and yet is economical to produce and avoids the known problems with the prior art devices.